Welcome to APSIM

The Agricultural Production Systems sIMulator (APSIM) is internationally recognised as a highly advanced simulator of agricultural systems. It contains a suite of modules which enable the simulation of systems that cover a range of plant, animal, soil, climate and management interactions. APSIM is undergoing continual development, with new capability added to regular releases of official versions. Its development and maintenance is underpinned by rigorous science and software engineering standards. The APSIM Initiative has been established to promote the development and use of the science modules and infrastructure software of APSIM.

NEWS

Modelling leaching losses from grazed systems

Leaching losses from grazed systems are notoriously hard to measure and to model because they are primarily generated from the deposition of urine patches and are therefore very spatially variable. Researchers from AgResearch in New Zealand have validated the ability of APSIM to predict leaching from urine patches in grazed systems and some of that work has been presented at the annual Fertilizer and Lime Research Centre Workshop “Adding to the Knowledge Base for the Nutrient Manager” earlier this year. Papers presented include work on leaching losses from urine patches, pre-experimental modelling on the interaction of fertiliser and urine patches, and nitrification inhibitors to reduce leaching.

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FEATURES

The global area and farming systems to which APSIM can be applied with confidence to have recently expanded with a research article recently published in the European Journal of Agronomy. A validation analysis showed that APSIM was able to accurately simulate the forage yield and water productivity of a range of forage crops and also continuous forage crop rotations across the Argentinian Pampas. Forage crops that the model was tested for includes maize, soybean, wheat, oats, annual ryegrass and barley. Water productivity was simulated with a greater accuracy when considering the whole crop rotation rather than individual crops. Crop forage yield simulated with greater accuracy for crops harvest without regrown compared to crops harvested frequently and allowed to regrowth.

For further details see the new paper titled ‘Modelling forage yield and water productivity of continuous crop sequences in the Argentinian Pampas’ published in European Journal of Agronomy at https://doi.org/10.1016/j.eja.2017.10.004.

In a paper recently accepted for publication in Global Change Biology (published open access), APSIM has contributed to an assessment of the ability of simulation models to simultaneously predict yield and N2O emissions. The study included five variants of APSIM (two in the crop part of the study and three in the grasslands part). In this study the modellers started with little site information (soil properties, weather data, management information) as Stage 1 and incrementally more data was supplied until in Stage 5 modellers had all available data. Crop model outputs improved at Stage 3 when phenology information was made available but grassland model outputs were little affected by the availability of additional information. As with other intercomparisons, the ensemble median performed better than any one model when considering multiple sites. It was found that a small ensemble of three models outperformed the full ensemble. This is the first study which has examined the effect of data availability of the performance of an ensemble and also the first examining both yield and N2O emissions.

APSIM is now being used in over 110 countries around the world. For the 2016/17 reporting year there were just over 1870 R&D non-commercial licensed users, around a 10% increase on the previous year. This resulted in some 2960 downloads of all versions. A copy of the APSIM users map is available here.

To model crop growth under the higher atmospheric carbon dioxide concentrations that will occur in the future, there needs to be and accurate representation of the link between atmospheric carbon dioxide concentrations and growth.

A review of APSIM’s crop models showed that carbon dioxide fertilisation effects were well founded, tested and documented in a number of important (mainly C3 crops) crops, notably wheat. There was agreement that many of these well founded representations could be generalised to other crops with similar photosynthetic pathways (e.g. generalising the science in wheat to other C3 crops). The situation was less well substantiated in crops with the C4 photosynthetic pathway.

The overall conclusion is that for a range of important crops, the general situation of representing carbon dioxide fertilisation effects on photosynthesis and transpiration in APSIM was close to the ‘state of the art’ given current understanding of, and data on the processes involved, and the aims of the APSIM model. There is an immediate need for better documentation of the representation of carbon dioxide fertilisation in APSIM, and a strategic need for further research and model development in this area.

For further details see the new paper titled Responses to atmospheric CO2 concentrations in crop simulation models: a review of current simple and semicomplex representations and options for model development published in Global Change Biology at the following link.

The current status of the representation, parameterisation and validation of CO2 fertilisation of plants in APSIM compiled by Vanuytrecht and Thorburn is also available here.

More than 300 scientists from 47 nations met in Berlin, Germany, during March 15-17, 2016 to exchange ideas on improvement and application of crop simulation models to better predict agricultural production and food security under global climate change. The symposium was co-organized by MACSUR (Modelling European Agriculture with Climate Change for Food Security, http://macsur.eu/) and AgMIP (Agricultural Model Intercomparison and Improvement Project, http://www.agmip.org/), and was locally hosted by the Leibniz Centre for Agricultural Landscape Research (ZALF) in Müncheberg, Germany.

During the 3-day meeting, there were a total of 85 presentations and 130 poster presentations. There were plenary lectures by James Jones (University of Florida, USA; The next Generation of Crop Models), Serge Savary (INRA, Toulouse, France; Models for Crop Diseases), Graeme Hammer (University of Queensland, Australia; Modelling and Genetics), Andrew J. Challinor (University of Leeds, UK; Models and Climate), Brian Keating (CSIRO, Australia; Models and Cropping Systems) and Achim Dobermann (Director of Rothamsted Research). Closing plenary lecture was given by Prof. Martin Kropff (Director General of the International Maize and Wheat Improvement Center, CIMMYT).